* {
  margin: 0;
  padding: 0;
  -webkit-box-sizing: border-box;
  box-sizing: border-box;
}

:root {
  --color-1: #11303a;
  --color-2: rgba(255, 255, 255, 0.75);
  --color-3: rgba(255, 255, 255, 0.5);
  --color-4: #215b6e;
  --color-5: #ffffff;
  --p-1: 10px;
}

body {
  font: normal 16px 'Microsoft YaHei', '微软雅黑';
  background: url(bg.jpg) no-repeat center center;
  background-attachment: fixed;
  background-size: cover;
  background-color: var(--color-1);
  color: var(--color-1);
}

#login-box {
  max-width: 520px;
  background-color: var(--color-3);
  -webkit-backdrop-filter: blur(7.5px);
  backdrop-filter: blur(7.5px);
  margin: 7em auto 0;
  border-radius: var(--p-1);
  border: 1px solid var(--color-2);
  padding: 3em 2em;
}

#login-box ::-moz-selection {
  color: var(--color-1);
  background-color: var(--color-2);
}

#login-box ::selection {
  color: var(--color-1);
  background-color: var(--color-2);
}

#login-box .form-box {
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-orient: vertical;
  -webkit-box-direction: normal;
  -ms-flex-direction: column;
  flex-direction: column;
  -webkit-box-align: center;
  -ms-flex-align: center;
  align-items: center;
}

#login-box .form-box button,
#login-box .form-box input {
  font-size: 100%;
}

#login-box .form-box #title {
  font-size: 2.5em;
  font-weight: bold;
  margin-bottom: 0.75em;
  text-shadow: 0 0 5px var(--color-3);
}

#login-box .form-box .input-box {
  position: relative;
  width: 100%;
  height: 3.5em;
  margin-bottom: 1.5em;
  border-bottom: 2px solid var(--color-1);
}

#login-box .form-box .input-box label,
#login-box .form-box .input-box .login-icon {
  position: absolute;
  top: 50%;
  -webkit-transform: translateY(-50%);
  -ms-transform: translateY(-50%);
  transform: translateY(-50%);
}

#login-box .form-box .input-box label {
  color: var(--color-1);
  font-size: 1em;
  font-weight: bold;
  opacity: 0.5;
  left: 0;
  -webkit-transition: all 0.35s;
  -o-transition: all 0.35s;
  transition: all 0.35s;
}

#login-box .form-box .input-box .label-top {
  opacity: 0.35;
  top: -10px;
  -webkit-transform: translateX(-5px) scale(0.85);
  -ms-transform: translateX(-5px) scale(0.85);
  transform: translateX(-5px) scale(0.85);
}

#login-box .form-box .input-box .login-icon {
  right: 5px;
}

#login-box .form-box .input-box input {
  background-color: transparent;
  border: none;
  outline: 0;
  height: 100%;
  width: 100%;
  color: var(--color-1);
  font-size: 1.25em;
  font-weight: bold;
}

#login-box .form-box .btn-submit {
  border: none;
  display: block;
  margin-top: 0.75em;
  width: 100%;
  padding: 0.9em 0;
  border-radius: 5px;
  font-weight: bold;
  font-size: 1.25em;
  color: var(--color-2);
  background-color: var(--color-1);
  -webkit-transition: all 0.35s;
  -o-transition: all 0.35s;
  transition: all 0.35s;
}

#login-box .form-box .btn-submit:hover {
  color: var(--color-5);
  background-color: var(--color-4);
}

#login-box .form-box .btn-submit:active {
  -webkit-transform: scale(0.95);
  -ms-transform: scale(0.95);
  transform: scale(0.95);
}